Modern drawer slides commonly in use today are of two basic types. The first type of drawer slide is one which uses two or three slides and after assembly the slide are not taken apart for installation into the cabinet. That is to say that the channel members are not designed to be separated from one another temporarily to be installed on drawers and cabinets. This first type of drawer slide can use an "open retainer" which can be manufactured from plastics or steel. An open retainer has seating apertures for the balls which have radii greater than that of the balls. After assembly the balls are prohibited from lateral displacement by the raceways of the mating flanges of an inner and outer slide channel member. The cage serves only to prohibit the balls from up and down and longitudinal displacement.
In the second type of drawer slide a retainer is used which has pressed and formed apertures which generally have a radius which is smaller than the radius of the ball. Such retainers after assembly secure the ball for rotation between the aperture and the inside portion of the flange of the outer channel. The inner channel flanges also contact portions of the balls when the slide is assembled but if the inner channel is removed the balls are maintained in place. This allows the file cabinet producer to affix the inner slide channel to the drawer and the outer slide channel to the cabinet during installation. Thereafter the slide channels are fitted back together and contact of the balls takes place on the adjacent raceways of the flanges of the outer and inner channels. It is this second type of modern drawer slide to which the present invention is directed.
In the second type of drawer slide the industry presently uses a generally standard bearing cage retainer which is made from a standard light guage piece of channel. Side flanges are folded upwards from the base and formed into a plurality of individual flanges on each side. An aperture is punched in each of the side flanges with the sides of the aperture pressed inwards to form a seat for the ball. The depressed pocket area formed is made in such a manner that the ball rests on the side edges of the aperture that is to say the points of contact are furthest away from the axis of rotation which is generally vertical running from the base of the retainer to the top of the flanges.
The inventor has found that such presently used retainers are not without problems. In particular there is a great amount of friction created at the points of contact between the apertures of the retainer and the balls. During normal slide travel the ball is supported on the friction surfaces. These points of contact occur on the portions of the ball with the highest surface velocity, consequently causing considerable resistance to rotation and promoting skidding of the ball along the slide channel raceways.
It is therefore an object of the present invention to provide a new ball retainer for use with two and three part drawer slides wherein friction between the ball and the retainer itself is significantly reduced.
It is also an object of this invention to provide a drawer slide of the second type (i.e. one in which the channels can be removed after assembly) has a significantly longer life span.